Ultrafast and thermally stable ternary Ge_0.33Se_xS_y ovonic threshold switching selector using magnetron sputtering

3D cross–point memory, with its cost efficiency and simple structure, has gained attention and commercial success. In this memory architecture, chalcogenide–based ovonic threshold (OTS) selectors are promising due to their fast, volatile, and reliable transition without altering their amorphous structure. GeS–based OTs selectors have recently emerged as potential candidates due to their thermal stability and high I_on. However, Ge_1−xS_x selectors suffer from slow switching times (t_on of 10 – 15 ns and t_off of 20 – 100 ns), hindering fast data processing. To address this, synthesizing Ge_1−xSe_x into Ge_1−xS_x is proposed as an effective method, as it reduces the activation energy (E_a) of Ge_0.33Se_xS_y, resulting in shorter t_on. This study presents a thermally stable and ultrafast OTS selector based on Ge_0.33Se_xS_y (0.22 ≤ x ≤ 0.55) films. There films remain amorphous after annealing at 600 °C. the device with the highest Se composition (x = 0.55) exhibits a short t_on of 6 ns and t_off of 13 ns. Ge_0.33Se_xS_y devices show varying V_th (3.6 to 2.8 V) as the Se/S ratio increases, along with low I_off (up to 1.2 nA). Further analysis using a modified Pool–Frenekl model reveals crucial parameters, and optical properties changes as the Se/S ratio increases. This ultrafast and thermally stable OTS selector promises outstanding performance for X–point memory architecture.